1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to triggering aperiodic sounding reference signals (SRSs) in a Carrier Aggregation (CA) configuration.
2. Background
Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.
A wireless communication network may include a number of base stations that can support communication for a number of user equipments (UEs). A UE may communicate with a base station via the downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station.
A base station may transmit data and control information on the downlink to a UE and/or may receive data and control information on the uplink from the UE. On the downlink, a transmission from the base station may observe interference due to transmissions from neighbor base stations. On the uplink, a transmission from the UE may cause interference to transmissions from other UEs communicating with the neighbor base stations. The interference may degrade performance on both the downlink and uplink. Previous technology supported periodic sounding reference signal (SRS) transmission on the uplink (UL) to facilitate features such as UL frequency-selective scheduling, UL power control, time tracking, and downlink scheduling utilizing UL-DL (uplink-downlink) channel reciprocity for Time Division Duplex (TDD).
Aperiodic SRS transmissions can be triggered by uplink grants, but the details of triggering of dynamic aperiodic SRS in the case of multiple uplink CCs (component carriers) was not previously determined.